elisp: support elisp files in subdirectories properly

elisp: support elisp files in subdirectories properly

For more reference, see:
<http://lists.gnu.org/archive/html/automake/2009-10/msg00013.html>
<http://thread.gmane.org/gmane.comp.sysutils.automake.bugs/4772>

* lib/am/lisp.am (.el.elc): If the file being byte-compiled is in
a subdirectory, add that (both as a subdirectory of the builddir
and the srcdir) to the emacs load path.  While we are at it (and
for consistency), drop quoting of $(srcdir) and $(builddir), since
those variables are ensured (by configure-time checks) not to
contain white space nor shell metacharacters.
* t/list-of-tests.mk (XFAIL_TESTS): Add 't/lisp-subdir.sh' and
't/lisp-subdir2.sh', since they now passes.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>